硫化铅量子点的合成及其新型异质结光伏器件的研究

发布时间：2018-05-25 21:33

本文选题：硫化铅量子点 + 异质结　；参考：《合肥工业大学》2017年博士论文

【摘要】：PbS是直接带隙半导体材料,具有很高的吸收系数,块体材料的带隙为0.41e V,其激子波尔半径为18nm,通过控制合成条件很容易得到具有量子效应且能带大小可控的PbS量子点,用以单结或多结的PbS量子点电池的制备。此外,PbS量子点还具有很强的多激子产生能力,在过去的数十年中,基于PbS量子点电池的研究受到科研人员的广泛关注,转化效率也有了突飞猛进的发展。但是相比目前已经发展成熟的第一代和第二代太阳能电池来说,PbS量子点电池的转化效率仍然偏低,电池性能的稳定性相对较差,此外在PbS量子点合成方面由于硫源活性的限制,使得用于光伏电池的PbS量子点合成方法仍然单一,合成成本难以降低,并且电池的组装过程难以面向大规模的工业化生产,这些都是其进一步的商业化发展的不利因素。因此发展绿色、廉价、大规模的量子点合成和器件组装工艺,并进一步研究电池机理和提高电池转化效率具有十分重要的意义。针对以上,本文从构建PbS量子点异质结电池出发,使用n型CdS替代电子传输层材料。从PbS量子点的合成出发,使用阳离子交换的方法获得单分散性良好,尺寸可控的PbS量子点,并使用这种量子点构建多结异质结电池。主要研究成果如下:1.发展了使用TMS作为硫源得到单分散性良好且性能稳定的PbS量子点的技术路线。使用油酸合成的CdS量子点的十八烯溶液作为前驱体提供反应所需的硫源,以PbCl_2/OLA和PbNO_3/OLA的前驱体溶液作为反应的铅源,使用离子交换的方法得到吸收峰位于800-1202nm范围内具有良好单分散性的PbS量子点并探索了在这种离子交换过程中阳离子的固态扩散机制。这种方法解决了传统硫粉活性较低和TMS价格昂贵,稳定性较差的问题,为合成单分散性良好且尺寸可控的PbS量子点和量子点表面的无机配体原位钝化提供了一个新的思路。2.通过对反应时间,反应溶液浓度等的调控,实现了CdS薄膜在FTO表面上的可控生长。在此基础上旋涂组装PbS量子点薄膜层,构建新型CdS/PbS量子点异质结光伏电池。通过插入MoO_3层得到PbS量子点与金属电极之间良好的欧姆接触,改善空穴传输性能,CdS薄膜的厚度的优化处理,得到了目前在CdS/PbS异质结结构中报道的最高5.22%的转化效率。化学浴沉积的方法具有合成温度低,合成范围大,对衬底材料的可选择性大的优点,为大规模的工业化生产提供了前景,同时在制备过程发现的电池性能对CdS薄膜厚度强烈的依赖性也为此类光伏器件的构建提供了很好的参考价值。3.使用化学浴沉积的方法在FTO上沉积一层CdS籽晶层,并结合水热法生长出CdS纳米棒阵列。将PbS量子点旋涂渗入纳米棒阵列的间隙位置,组装了这种基于CdS纳米棒阵列的3D异质结结构的量子点光伏电池。通过调控CdS籽晶层的厚度来调节纳米棒阵列的间隙,PbS量子点溶液的旋涂速度改善其渗透性,对不同旋涂层数的PbS薄膜的表面形貌的扫描电镜图像、透射光谱和转化效率进行实时监控,得到最优层数的致密3D异质结结构。最后获得了最高4.78%的转化效率,相比同样厚度的平面层有了明显提升。4.使用阳离子交换得到PbS量子点,利用TBAI和EDT配体交换的量子点薄膜能带结构不同的特征,构建了TiO_2/PbS结构的多结异质结量子点电池。通过多结异质结的构建,卤素离子的钝化,得到了7.89%的最高转化效率,短路电流,开路电压和填充因子分别为30.96m A/cm2,0.49 V和51.9%。研究了在这种多结结构中由于EDT层较高的导带位置载流子单向的传输机制,TBAI层和EDT层在光活性层中的主要作用等。此外,卤素离子钝化的量子点电池具有较长的载流子扩散长度,在空气中具有很好的稳定性,同样这种异质结电池可作为自驱动式的光电探测器,具有较快的响应速度,在10k Hz的脉冲光下上升沿和下降沿的时间分别为4.4μs和37.2μs。
[Abstract]:PbS is a direct band gap semiconductor material with high absorption coefficient, the band gap of block material is 0.41e V and its exciton Bohr radius is 18NM. By controlling the synthetic conditions, it is easy to obtain the quantum dots with quantum effect and controllable size of PbS quantum dots, which are used for the preparation of single or multi junction PbS quantum dots batteries. In addition, PbS QDs are also available. In the past few decades, the research on PbS quantum dot batteries has been widely concerned by researchers, and the conversion efficiency has developed rapidly in the past few decades. However, the conversion efficiency of PbS QDs battery is still low compared with the mature first and second generation solar cells. The stability of the pool performance is relatively poor. In addition, due to the limitation of the sulfur source activity in the synthesis of PbS quantum dots, the synthesis of PbS quantum dots used in photovoltaic cells is still single, the cost of synthesis is difficult to reduce, and the assembly process of the battery is difficult to face large-scale industrial production. These are all its further commercialized development. Therefore, it is of great significance to develop green, cheap, large-scale quantum dot synthesis and device assembly processes, and to further study the mechanism of the battery and to improve the efficiency of the battery conversion. In this paper, we use the n CdS to replace the electron transport layer materials from the construction of PbS quantum dot heterojunction cells. The synthesis of PbS quantum dots is made in this paper. On the basis of the cation exchange method, the PbS quantum dots with good monodisperse, size controlled quantum dots and multi junction heterojunction batteries were constructed by using this quantum dot. The main research results are as follows: 1. the technical route of using TMS as a sulfur source to obtain good monodisperse and stable PbS quantum dots is developed. The CdS quantum synthesized by oleic acid is used. The point eighteen alkene solution is used as the precursor of the precursor to provide the sulfur source. The precursor solution of PbCl_2/OLA and PbNO_3/OLA is used as the lead source of the reaction. By ion exchange, the PbS quantum dots with good monodispersity within the range of 800-1202nm are obtained and the solid state expansion of the cation in this ion exchange process is explored. This method solves the problem of low activity of traditional sulfur powder, high price of TMS and poor stability. It provides a new idea for the synthesis of PbS quantum dots with good monodisperse and size controlled inorganic ligands on the surface of quantum dots..2. has realized the CdS thin through the regulation of the reaction time, the concentration of the reaction solution and so on. The controllable growth of the membrane on the FTO surface. On this basis, the PbS quantum dots film layer was assembled by spin coating, and a new CdS/PbS quantum dot heterojunction photovoltaic cell was constructed. The good ohmic contact between the PbS quantum dots and the metal electrodes was obtained by inserting the MoO_3 layer to improve the hole transmission performance and the optimization of the thickness of the CdS film, and the current CdS/PbS was obtained. The highest 5.22% conversion efficiency reported in the heterostructure. The chemical bath deposition method has the advantages of low synthesis temperature, large synthesis range and high selectivity to substrate material, which provides a prospect for large-scale industrial production. At the same time, the battery performance found in the preparation process is also dependent on the strong dependence of the thickness of CdS film. The construction of the volt device provides a good reference value.3. using a chemical bath deposition method to deposit a layer of CdS seed crystal on the FTO, and the CdS nanorod array is grown by the hydrothermal method. The PbS quantum dots are swirled into the gap position of the nanorod array, and the quantum dot photovoltaic power of the 3D heterojunction structure based on the CdS nanorod array is assembled. The clearance of the nanorod array is regulated by regulating the thickness of the CdS seed layer. The spin coating speed of the PbS quantum dots solution improves its permeability. The scanning electron microscope images, transmission spectra and conversion efficiency of the surface morphology of the PbS films with different layers of spin layers are monitored in real time, and the optimal layer number of dense 3D heterostructure is obtained. Finally, the structure of the compact 3D heterostructure is obtained. The maximum conversion efficiency of 4.78% is significantly higher than the same thickness of the plane layer..4. uses the cation exchange to obtain the PbS quantum dots. The quantum dot films with TBAI and EDT ligands have different structure characteristics, and the multi junction heterojunction quantum dot cells of the TiO_2/PbS structure are constructed. The maximum conversion efficiency of 7.89% is obtained. The short circuit current, the open circuit voltage and the filling factor are 30.96m A/cm2,0.49 V and 51.9%., respectively, to study the unidirectional transmission mechanism of the carrier position of the higher conduction band in the EDT layer, the main role of the TBAI layer and the EDT layer in the photoactive layer. In addition, the amount of halogen ion passivation. The sub cell has a long carrier diffusion length and has a good stability in the air. The same heterojunction battery can be used as a self actuated photoelectric detector. It has a fast response speed. The time of rising and falling along the pulse light of 10K Hz is 4.4 Mu s and 37.2 S. respectively.
【学位授予单位】：合肥工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB383.1;TM914.4

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